As a wireless transmission device of the related art, a wireless transmission device in which a transmission and reception device estimates a transmission path situation based on a received signal, satisfies communication quality of a fixed level in a propagation path situation, and deter nines a modulation scheme representing a highest transmission speed as a first modulation scheme is known (for example, see Patent Document 1).
The wireless transmission device disclosed in Patent Document 1 detects a traffic volume of transmission data and determines a modulation scheme representing a lowest transmission speed at which the traffic volume can be transmitted as a second modulation scheme.
This wireless transmission device selects a modulation scheme of a lower transmission speed within the first modulation scheme and the second modulation scheme as a transmission modulation scheme.
Further, this wireless transmission device reduces power consumption by sequentially selecting modulation schemes so that a wireless transmission capacity according to a traffic volume is provided.
As a wireless transmission device of the related art, a wireless transmission device using a communication traffic volume in information for determining communication capability according to a communication control function is known (for example, see Patent Document 2).
The wireless transmission device disclosed in Patent Document 2 uses a communication time zone in the information for determining the communication capability according to the communication control function.
This wireless transmission device can implement optimum communication capability and optimum power consumption according to the communication traffic condition and implement optimum communication capability and optimum power consumption according to the communication time zone.
In this manner, various proposals for a method of reducing power consumption of a wireless transmission device by controlling an adaptive modulation circuit and wireless transmission power based on a traffic volume of a transmission signal have been made so far.
As general technology, when a multi-level number of the wireless modulation scheme increases, a wireless transmission capacity increases but error tolerance of the wireless transmission path is degraded. When the multi-level number of the wireless modulation scheme decreases, the wireless transmission capacity decreases but high error tolerance is securable.
That is, when a modulation scheme of a small multi-level number is used on the same wireless propagation condition, a good propagation characteristic can be obtained at lower transmission power.
Normally, it is known that, although the traffic volume is varied in real time, there is a correlation between an operation time zone and a traffic volume.
In particular, when a discontinuous signal stream is transmitted using a wireless transmission device which continuously performs wireless transmission and reception, wireless transmission and reception are constantly maintained even in a state in which there is no traffic to be transmitted.
Because fixed power is constantly consumed even in a situation in which the traffic volume has been reduced, power control according to a line state or traffic volume is required.